The present invention relates to a clarification plant with at least one activation tank which is provided with a surface ventilation rotor provided adjacent the outlet of a vertically oriented conduit therein for recycling activated sludge emanating into the conduit from a re-clarification tank.
Clarification plants in which activated sludge is recycled from a reclarification tank into an activation tank are known. However, such known plants suffer from the disadvantage that it is necessary in order to recycle the activated sludge back into the activation tank to have an additional capacity-consuming conveyor unit, and the activated sludge in the activation tank comes into contact with too little oxygen per unit of time.